I have soldered very simple project on nano v3 includes i2c oled 128x32, pushbutton with certain sequence to change display data and isolated optocoupler used as 220 to 5V adapter (the project should count numbers of connections to 220V). When I power it from USB it works fine. But I need to power…

Works fine powered from USB works bad powered externally

ilyagin November 12, 2021, 6:19pm 4

12V/400mA
I'm sorry for inconvenience that it is in Russian :

AC/DC converter

OLED display: